Truck and auto wash apparatus are generally well known in the art. A great variety of configurations have been and are being employed in the field. These vary from largely manually operated devices to nearly completely automated machines. Whether the washing fluids are applied to a vehicle by an automated gantry, or the like, or by a hand held wand, there must be some method or means for mixing chemicals, such as soaps, with the water. Such method or means should be accurate, economical and reliable.
There are several methods in use, all of which have some problem or another. One method is downstream injection, whereby the pressure of the water flow is reduced to a point that a venturi injector can be used. This is inefficient and difficult for the operator, since the operator has to constantly change the pressure at the gun. Another method is upstream injection. This is also a problem, since it takes so long for the chemical to get to the selected spray nozzles from the equipment room, thereby wasting time, chemicals, and water.
Another method which has been used is to separate the chemical from the high pressure water completely by providing chemical laden water in a separate supply line pressurized by an air driven pump. This works well, but the chemical and water must be premixed, which is time consuming and requires additional holding tanks. Furthermore, according to this particular prior art method, anytime the discharge valve is open the product flows, whether that is the intention or not.
It would be beneficial to have a method or apparatus whereby chemicals could readily be mixed with water in a vehicle wash system which would not waste chemicals and/or time, and which would be reliable and accurate in operation. However, to the inventor's knowledge, all prior art systems have suffered from one or more of the problems discussed previously herein.